Tear away or contact fastening systems are well known. Such systems incorporate two opposing segments of material which are engageable in substantially juxtaposed relation to one another. A male portion of such a contact fastening system typically incorporates a plurality of outwardly projecting hooking structures, while the female portion incorporates a plurality of outwardly projecting loop structures. Upon engagement between the two cooperating portions, the hooking structures engage the opposing loop structures thereby establishing a bond. This bond may be broken by the application of a peeling action between the two opposing portions of material thereby permitting the male and female portions to be progressively disengaged from one another. The engagement may be reactivated by simply bringing the male and female portions back into contacting juxtaposed relation with one another.
In many environments, it is desirable for the connection between the hooking portion and the loop portion to remain secure during use. The strength of the bond formed by the hook and loop portions may be measured both in terms of peel strength and shear strength. In this regard, peel strength is the magnitude of the force required to pull the hook and loop portions away from one another by application of a pulling force having a direction oriented substantially normal to the plane defined by the interface between the joined materials. Accordingly, peel strength is generally reflective of the separating force experienced under normal use conditions. A standard technique for measurement of peel strength is set forth in ASTM standard 5170, the contents of which are incorporated herein by reference.
Shear strength is the magnitude of the force required to move the hook and loop portions away from one another by application of a pulling force having a direction oriented substantially parallel to the plane defined by the interface between the joined materials. A standard technique for measurement of shear strength is set forth in ASTM standard 5169, the contents of which are incorporated herein by reference.
Stitch-bonding is a known process in which yarns are stitched through a substrate to form a coordinated web structure. By way of example only, and not limitation, exemplary stitch-bonding processes are disclosed in U.S. Pat. Nos. 6,855,392; 6,869,660; and 7,294,387 all of which are incorporated by reference as if fully set forth herein. In the past, it has been difficult to achieve a combination of both high peel strength and high shear strength in a fastening system incorporating a loop fabric of stitch-bonded